Double-seal plastic cap with flexible rim-engaging flange

ABSTRACT

A one-piece plastic cap, primarily for glass bottles, having two separate annular sealing areas, one formed by a hollow cylindrical stopperlike portion extending down from the top of the cap into the neck of a bottle or other container, and the other sealing portion formed by a flexible rim-engaging flange extending out in skirtlike fashion from the cylindrical portion near its top and deformable upwardly by the pouring rim of a bottle or the like into conformity with the rim contour at all points around the engaged portion of the rim.

United States Patent inventor Milton Kessler jfiy lli n' t edm qwez Ohio 44512 Appl. No, 884,673 Filed Dec. 12, 1969 Patented Jan. 4, 1972 DOUBLE-SEAL PLASTIC CAP WITH FLEXIBLE RIM-ENGAGING FLANGE 3 Claims, 7 Drawing Figs.

US. Cl 215/41, 215/47, 215/40 Int. Cl 365d 41/22 Field of Search 215/40, 41, 43,47,D1G. 1

[56] References Cited UNITED STATES PATENTS 3,055,526 9/1962 Plunkett 215/43 FOREIGN PATENTS 1,342,700 9/1963 France 215/41 Primary Examiner-George T. Hall AttorneyMax L. Libman ABSTRACT: A one-piece plastic cap, primarily for glass bottles, having two separate annular sealing areas, one formed by a hollow cylindrical stopperlike portion extending down from the top of the cap into the neck of a bottle or other container, and the other sealing portion formed by a flexible rim-engaging flange extending out in skirtlike fashion from the cylindrical portion near its top and deformable upwardly by the pouring rim of a bottle or the like into conformity with the rim contour at all points around the engaged portion of the rim.

PATENTED JAN 41972 INVENTOR I 0 n K as s I er ATTORNEY DOUBLESEAL PLASTIC CAP WITH FLEXIBLE RIM- ENGAGING FLANGE Efforts have been made to provide a linerless, one-piece plastic cap for bottles, usually of reason, screw type, but including other forms such as the snap-top cap having an internal rim which snaps over an external rim of the pouring spout to hold the cap in place. Such efforts are exemplified by U.S. Pat. Nos. 3,232,470 and 3,069,040, both of which attempt to rely upon the principle of having two sealing areas in order to achieve greater reliability of sealing. Such caps are primarily intended for use with glass bottles, although they may also be used with other types of containers such as plastic or metal. A difficulty in the case of glass bottles is that the manufacturing methods used in providing inexpensive glass bottles requires a considerable amount of dimensional tolerance, that is, the necks of the bottles may be out of round by 0.050 inch or more, and also the top rim of the pouring spout of the bottle may be somewhat irregular, that is, it may all not lie in a single plane. For this reason, it is customary in sealing bottle caps to provide a cushion of relatively soft and deformable material such as cork, rubber, or very soft plastic material, inside of a cap of rigid material such as metal, so that the soft material can be sufficiently compressed to engage the rim of the bottle at all points and thus provide adequate sealing. In making a one-piece plastic cap, for example, of the screw type, it is necessary that the cap material be sufficiently rigid so that it can be screwed down tightly when it is applied, and therefore the material must be sufficiently hard and incompressible so that it must be termed at least semirigid, which means that it cannot be compressed sufficiently to engage all points of a bottle rim, where the rim is irregular, sufficiently well to provide an adequate seal against leakage.

This degree of hardness is necessary for the threads to engage properly, as soft deformable material will begin jumping threads before sufiicient sealing pressure is attained.

The present invention overcomes the above difficulties by means of a novel construction, in a very simple manner, which enables the cap to be molded and readily stripped from the mold, even when it is made of a semirigid material as required for this purpose. Although the invention will be described in connection with a screw-type cap, it will be understood that it applies to any other type of cap which provides for engagement with the neck of a bottle under sufficient sealing pressure to prevent leakage of the fluid contents.

In accordance with the invention, an all-plastic cap is provided which has a hollow cylindrical stopperlike portion extending down from the top of the cap into the pouring spout or neck portion of the bottle in snug, stopperlike engagement therewith, and another sealing portion formed by a flexible rim-engaging flange extending out and down in skirtlike fashion from the cylindrical portion near its top but sufficiently far down from the top so that the skirt can be flexed down tight thereon. In other words, the flange must be attached to the cylindrical portion at a point definitely below the top of the cap, in order to produce the required sealing action, as will be described in more detail below.

The specific nature of the invention, as well as other objects and advantages thereof, will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing, in which:

FIG. I is a bottom view looking up into the interior of a cap according to the invention;

FIG. 2 is a transverse sectional view of the cap taken on line 2--2 of FIG. 1;

FIG. 3 is a view similar to FIG. 2, showing the cap screwed down on the neck of a bottle;

FIG. 3A shows the way in which the flange seals a bottle having an irregular lip;

FIG. 4 is a fragmentary view similar to FIG. 3 showing a tapered flange;

FIG. 5 is a view similar to FIG. 3 showing the effect when the flange is too wide; and

FIG. 6 is a fragmentary view similar to FIG. 5 showing the effect when the flange is too narrow.

Referring to FIGS. 1 and 2, the cap is shown as having a threaded wall w, although it will be understood that other forms of cap fastening may be employed. The wall 2 extends down from the top portion 3 of the cap, which is shown as flat, but may have any desired configuration, except that its bottom portion 30 should be substantially flat. Extending down from the top 3 is a hollow cylindrical stopperlike portion 4, preferably tapered at its bottom rim as shown at 40, in order to facilitate its insertion into the neck of a bottle or similar container. If desired, the entire cylinder may have a downward taper to further facilitate its engagement with the interior of a bottle neck. Flange 6 extends out in skirtlike fashion from cylinder 4 near its top at a downward angle sufficient so that the forming mold can be disengaged immediately after the skirt is formed, when it is still warm and very flexible, after which it resumes its original shape as shown, due to the elastic memory of the plastic molecules. In practice, it is not possible to mold the cap so that the flange 5 extends out at right angles from the cylinder 4, because in that case the stripping operation would tend to strip the flange away from the cylinder, so that a certain amount of downward angle must be given to the flange as shown, in order to enable mold stripping to be successfully accomplished. Although the flange is shown as of substantially uniform thickness from its base to its edge, it will be understood that it could also be tapered as shown in FIG. 4, to a very sharp edge, or may be provided with a smaller degree of tapering thickness if desired.

FIG. 3 shows the effect when the cap is screwed down onto the neck of a bottle 7, the top rim of the bottle engages the outer rim of the flange as shown at 8, and bends the flange upward until its outer edge is squeezed between the top of the bottle lip and the bottom portion 3a of the cap top, although the seal is also efiective if the flange edge does not quite engage the cap top. If the relation of the flange width to the thickness of the pouring spout of the bottle is substantially as shown in FIG. 3, then the flange will engage the top of the bottle at all points, even if the bottle rim is higher at one point than another, as shown in FIG. 3A, where the bottle rim at the left-hand side compresses the flange against the top of the cap, but on the right-hand side does not come up far enough to compress the rim as shown at 6b, leaving a small space between the flange and the top of the cap at this point. However, under these conditions, the outer edge of the flange is being subject to some compressional force of such a nature that it tends to flex downwardly and thus hug the rim of the bottle as shown at 6b, with considerable force, so as to provide a good fluid seal at this point. It should be noted that if the flange were too wide, and extended out beyond the rim of the bottle for too great a distance as shown in FIG. 5, the compressional circumferential force of the flange would be so great that the flange would tend to buckle at its edge or outer perimeter, and the effect shown in FIG. 5 would be produced, which would make it impossible to obtain a good seal. Likewise, if the flange were too short, as shown in FIG. 6, it would not be held firmly enough at its outer perimeter to provide a tight contact at all points sufficient to insure against leakage. While some variations in the width of the annular flange is permissible, in general it should extend out only a little beyond one-half of the thickness of the bottle neck, so that a reasonable amount of manufacturing inaccuracy can thus be accommodated.

It will be understood that the invention is not limited to the exact embodiment shown and that various modifications can be made in construction and arrangement within the scope of the invention.

I claim:

1. a. A one-piece double-seal semirigid plastic cap of substantially incompressible material, having two separate annular sealing areas, comprising b. a substantially flat top portion,

c. an exterior cylindrical skirt portion extending downwardly from the top portion and provided with means for engaging the exterior of a pouring spout so as of said skirt can be flexed upwardly by an engaged pourl ing lip until it comes into contact with said flat top, f. said annular flange in its unused condition extending out and down from the cylindrical portion in the form of a truncated cone.

2. The invention according to claim 1,

f. said flange extending out radially only a sufficient distance to contact the topmost portion of the pouring lip of an engaged pouring spout.

3. The invention according to claim 2, said annular flange being tapered in thickness from a maximum at its base, where it is joined to the cylindrical portion, to a minimum thickness at its edge.

i i t I i 

1. A. A one-piece double-seal semirigid plastic cap of substantially incompressible material, having two separate annular sealing areas, comprising b. a substantially flat top portion, c. an exterior cylindrical skirt portion extending downwardly from the top portion and provided with means for engaging the exterior of a pouring spout so as to press the top portion downwardly against the pouring lip of such spout, d. a hollow, generally cylindrical stopperlike portion extending down from the top of the cap into the interior of an engaged pouring spout in snug sealing relation with an interior cylindrical wall of said pouring spout, e. a thin, flexible, rim-engaging annular flange extending outwardly as a skirt from said cylindrical stopper below the bottom of the flat top portion by an amount less than the width of the flange, so that the edge of said skirt can be flexed upwardly by an engaged pouring lip until it comes into contact with said flat top, f. said annular flange in its unused condition extending out and down from the cylindrical portion in the form of a truncated cone.
 2. The invention according to claim 1, f. said flange extending out radially only a sufficient distance to contact the topmost portion of the pouring lip of an engaged pouring spout.
 3. The invention according to claim 2, said annular flange being tapered in thickness from a maximum at its base, where it is joined to the cylindrical portion, to a minimum thickness at its edge. 